Phase Behavior of Organogel Solutions
The talk will focus on the relationships between the thermodynamic phase behavior and gelation behavior of 12-hydroxystearic acid (12-HSA) in organic solvents. In particular, the role of 12-HSA aggregation in the liquid state on the melting point depression will be discussed. Measurements of the liquids lines of 12-HSA in different dialkyl phthalates have been made. This data could be fit with Flory diluent model, which accounts for both the non-ideal free energy of mixing and the disparity in the size of the solvent and 12-HSA molecules. The fits showed that the effective molar volume of 12-HSA increased as the hydrogen bonding Hansen solubility parameter δh of the solvent decreased. This is consistent with a variation in the size of 12-HSA aggregates in the liquid state as a function of the choice of solvent. It will be shown that this aggregation is useful to stabilize 12-HSA crystalline networks (and the resultant gels) at higher temperatures and lower concentrations through a reduction in the entropy of mixing. The general use of molecular size to tune solution phase behavior and design organogelators will also be discussed.
Abstracts of Papers of the American Chemical Society
Cavicchi, Kevin, "Phase Behavior of Organogel Solutions" (2014). Polymer Engineering Faculty Research. 2327.